1. Field of the Invention
The present invention relates to a clip-on shield for spectacles wherein the shield is secured to the spectacles by means of a clip-on device to allow occasional use thereof over ordinary lenses.
The invention further relates to a combination of a removable shield and a pair of spectacles.
The term "spectacles" is used herein to designate the well known optical accessory which basically comprises a pair of lenses made from glass or other refractive material, usually made according to an optician's prescription and intended for being worn by a wearer in order for him to enjoy an optically corrected view by seeing through them, and provided with fitting means for conveniently securing the lenses in the preferred in-use position in which the wearer is offered the possibility of looking straight through the respective lenses while both eyes have generally parallel directions of vision.
Occasionally a bespectacled person may want to use a pair of auxiliary lenses together with his or her spectacles, most often a pair of tinted lenses adapted for reducing sunglare. Although such items are referred to herein as lenses, this is not intended to signify that they would necessarily include optically refractive means, in most cases they rather include some type of optical filters known in the art.
As generally known in the art, the occasional use of auxiliary lenses by bespectacled persons is facilitated by fitting the lenses in the form of a detachable shield, i.e. in the form of an accessory with fitting means adapted for detachable fastening onto the spectacles in such a manner that the shield lenses are secured in a position to substantially cover the ordinary lenses in a slightly spaced surface to surface relation. Such a shield essentially comprises two shield lenses, a bridge designed to straddle over the wearer's nose and means for detachable fitting of the shield acccessory over the spectacles.
2. Description of the Prior Art
DE patent No. 27 18 445 teaches an accessory shield which comprises two clips or clamps arranged to allow the accessory shield to be mounted on the spectacles by being shifted downwards over the spectacles from above and constructed to obtain flexible securing by means of tongues which engage and clamp the front and the back of each of the lenses in a substantially vertically extending area adjacent to the inner rim, i.e. generally close to the wearer's nose. Each of the clips is further provided with a connecting branch adapted for abutment on a top frame portion of the spectacles.
Although simple and commonly used, shields of this general type are associated with certain drawbacks. From an aesthetical point of view, they are rarely accomplished since they easily slide and become awry. Usually, the abutment on the top frame of the spectacles is not sufficient to ensure stable centering and perfect orientation, since most often the top frame of the spectacles extends in a curved manner, which means that the shield comes to rest on a curved area where the shield is likely to slide sideways. In order to provide such a shield with the capacity of fitting over any among a range of spectacles where the spacing between the inner rims of the lenses and the corresponding rims of the frame, respectively, varies, the clips must be adapted with a width sufficient to straddle the wider spacing. Hereby the clips will on the majority of spectacles, where the rim spacing is average or below average, engage the lenses at zones relatively far away from the rims.
Moreover, it is difficult to ensure stable fitting of the flexible clips onto any thickness of frames and lenses, and since different wearers wear different thicknesses of frames and lenses, some wearers are unable to use shields with this type of fastening means.
During mounting and dismounting the flexible clips are to slide up and down over the support areas in the full vertical extent of the clip which involves a risk of scratching both the front and the back of the lenses. Often, the movement becomes irregular with lateral displacements due to the two spring clips engaging curved portions of respective lens rims, while the user attempts to displace the shield vertically. This means that the area exposed to such scratching is comparatively large. In case of lenses made of glass, this does not present a problem, however, in case of lenses made from plastics, it is not acceptable.
Since many wearers prefer plastic lenses, e.g. because they favor low weight or shatterproofness, fastening means which do not cause scratching problems are very much in demand.
The movement for applying the shield onto the spectacles as well as the movement for removing the shield are generally oriented parallel to the plane of the glass surfaces. This manipulation is difficult to accomplish without the user having to remove the spectacles.
U.S. Pat. No. 5,920,369 discloses a removable shield with a central connection bridge provided with hook projections adapted to engage the spectacle nose bridge. The shield may also be provided with guide pegs in lateral positions, oriented generally perpendicular to the glasses and adapted to engage apertures in the spectacle frame adjacent the hinges. This shield is applied from the front. Application of this shield neccesitates registrering the hook projections with the nose bridge and registering the lateral pegs. Generally the user will register first the hook projections and will subsequently register the pegs, one at a time. This shield achieves a good fit and a good hold on the spectacles, but at the cost of a somewhat complicated handling which the user may not find easy, at least not unless the spectacles are removed during this operation.
U.S. Pat. No. 5,614,963 illustrates a combination of a removable shield and a pair of spectacles in which the spectacle frame is provided with lateral protuberances, each protuberance being provided with a bore, which bore is oriented generally perpendicular to the glass surfaces. The shield is provided with lateral pin members adapted for registering in respective bores. The pin members may be bifurcated with fork ends adapted for securing the shield. The part of the shield intermediate the pegs is secured to the glasses by means of patches of mating hook and loop pile fastening material.
Thus, this prior art relies on dedicated attachment means on the eyeglasses which may create an undesirable bulky look. The parts require delicate manufacturing and delicate matching, and additional means need to be provided in order to secure a good fit.